High-carbon razor blade stock and the like



United States Patent 2,987,429 HIGH-CARBON RAZOR BLADE STOCK Geo V Smlth,Ithnca,NY assign toU t dStat e or m e es teel Corporation, a corporation of New Jersey No Drawing. Filed Jan. 7, 1958, Ser. No. 707,464 8 Claims. (Cl. 148-12) This invention relates to the formation of cold-rolled, flat, high-carbon steel products produced by a plurality of cold reductions with intermediate spheroidizing annealing treatments, such as razor blade stock, which products are substantially free from graphite.

High-carbon razor blade stock and the like products are conventionally formed of steel containing over about 1.00% carbon. Due to the work-hardening characteristics of such steel, a plurality of cold-reducing operations with intermediate spheroidizing anneals are required to reduce hot-rolled strip from about .060" to .080" to less than .010". Frequently as many as 6 cold rollings and intermediate anneals are required. Such processing treatment has heretofore required the introduction of about .50% chromium into the steel to prevent graphitization during annealing, which is deleterious to certain articles such as razor blade stock. Chromium is of course quite an expensive element and also is on the list of strategic materials.

It is accordingly an object of this invention to provide high-carbon, cold-rolled and spheroidized steel characterized by freedom from graphitization and the absence of chromium.

In accordance with the teachings of my invention, steel for processing into high-carbon, flat, cold-reduced and spheroidized product is produced by basic open hearth or electric furnace practice to conventional specifications except that no chromium is added thereto. The steel is therefore typified by having less than .50% chromium and preferably no more than a residual chromium content of about .15% maximum. Such steel has a carbon content of about .75 to 1.50%, about .35 to 1.50% manganese, .50% maximum silicon, .05% maximum aluminum, with sulphur and phosphorus each less than .045%. The balance of the steel is substantially iron with residual amounts of other elements. In accordance with the teachings of my invention, nitrogen is added to the steel either while molten or after solidification to raise the content to a minimum of at least .010%. The nitrogen content should be in the range of .010 to .020%, preferably between about 0.12 and 0.15%. A convenient way of adding nitrogen to molten steel is by introducing calcium cyanide thereto. The steel after killing and the nitrogen addition is teemed into molds, allowed to solidify, stripped and soaked at conventional pit temperatures; thereafter it is hot rolled to about .06" to .08" gauge. If the nitrogen addition has not been added to the steel while molten, it can be added thereto by austenitizing in nitrogen for about 5 to 6 hours at 1900 F., or by heating in some other environment capable of introducing nitrogen; for example, dissociated ammonia.

The stock is then reduced to the desired thickness of less than .01" by repeated cold reductions with intermediate spheroidizing meals to suitably soften the steel to permit further cold reductions. Such annealing conventionally consists of holding the steel in the range of 1200 to 1400' F. for at least 2 hours followed by very slow cooling.

High-carbon, cold-reduced steel treated in accordance with the teachings hereof does not show any signs of graphitization even after quenching to martensite and reheating for 10 days at 1200' F.

This application is a continuation-impart of my co- Patented June 6, 1 961 pending application Serial No. 431,007, filed May 19, 1954, now abandoned.

While I have shown and described several specific embodiments of my invention, it will be understood that these embodiments are merely for the purpose of illustration and description and that other forms may be devised within the scope of my invention, as defined in the appended claims.

I claim:

1. As a new article of manufacture, substantially nongraphitized razor blade stock of less than .010" thickness composed of high-carbon, cold-reduced and spheroidized basic steel containing .75 to 1.50% carbon, .35 to 1.50% manganese, .50% maximum silicon, .50% maximum chromium, .05 maximum aluminum, .045 maximum sulphur and phosphorus and nitrogen in excess of .010% with the balance substantially iron and residual amounts of other elements.

2. A method of producing fiat, cold-reduced and substantially nongraphitized, spheroidized razor blade stock having a thickness less than .010" gauge from basic openhearth and electric furnace steel containing between about .75 to 1.50% carbon and less than .50% chromium, .045% maximum sulphur and phosphorus comprising adding between .012 and .015 nitrogen to the steel and then alternately cold-reducing and spheroidizing it.

3. A method of producing flat, cold-reduced and substantially nongraphitized, spheroidized razor blade stock having a thickness less than .010" from basic openhearth and electric furnace steel containing between about .75 and 1.50% carbon and less than .50% chromium, .045% maximum sulphur and phosphorus comprising adding at least .010% nitrogen to the steel and then alternately cold-reducing and spheroidizing it.

4. A method of producing flat, cold-reduced and substantially nongraphitized, spheroidized razor blade stock from basic open-hearth and electric furnace steel containing between about .75 and 1.50% carbon and less than .50% chromium, .045% maximum sulphur and phosphorus comprising hot rolling the steel to strip of about .06 to .08 gauge, heating said hot-rolled strip in a nitrogen containing atmosphere to raise the nitrogen content thereof to at least .010% and then alternately cold-reducing and spheroidizing to a final gauge of less than about .010".

5. As a new article of manufacture, a high-carbon, cold-reduced and substantially nongraphitized, spheroidized basic steel product containing .75 to 1.50% carbon, less than .5% chromium, .045% maximum phosphorus and sulphur and more than .012% nitrogen.

6. A method of producing flat, high-carbon, cold-reduced and substantially nongraphitized, spheroidized steel products from basic open-hearth and electric furnace steel containing .75 to 1.50% carbon, less than .50% chromium, .045% maximum sulphur and phosphorus comprising adding between 0.12 and 0.15% nitrogen to the steel and then alternately cold reducing and spheroidizing it.

7. A method of producing flat, high-carbon, cold-reduced and substantially nongraphitized, spheroidized steel products from basic steel containing .75 to 1.50% carbon, less than .50% chromium, .045 maximum sulphur and phosphorus comprising adding at least .012% nitrogen to the steel while molten and then alternately cold reducing and spheroidizing it.

8. A method of producing flat, high-carbon, cold-reduced and substantially nongraphitized, spheroidized steel products from basic open-hearth and electric furnace steel containing .75 to 1.50% carbon, less than .50% chromium, .045% maximum sulphur and phosphorus comprising hot rolling the steel to form strip, heating said hotrolled strip in a nitrogen atmosphere to raise the nitrogen content thereof to at least .010% and then alternately cold reducing and spheroidizing it.

References Cited in the file of this patent UNITED STATES PATENTS 2,174,740 Graham et a1 Oct. 3, 1939 2,531,731 Hibbflt NOV. 28, 1950 4 OTHER REFERHQCES Report on The Bessemer Process, the Iron and Steel Institute, pages 26 and 31, May 1949.

Making, Shaping and Treating of Steel, 6th ed., pp. 391, 531, 1239 and 1244, 1951.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,. 2,987,429 June 6 1961 George Va Smith It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 49 and column 2 line 56 for 0012 and O0 15%" each occurrence read .,O12 and O15% rug Signed and sealed this 24th day of October 1961 (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC 

5. AS A NEW ARTICLE OF MANUFACTURE, A HIGH-CARBON, COLD-REDUCED AND SUBSTANTIALLY NONGRAPHITIZED, SPHEROIDIZED BASIC STEEL PRODUCT CONTAINING .75 TO 1.50% CARBON, LESS THAN .5% CHROMIUM, .045% MAXIUM PHOSPHOROUS AND SULPHUR AND MORE THAN .012% NITROGEN. 